The enzymatic protein rennin has long been known as useful for coagulating milk casein in cheese making. It is also used in connection with cheese-ripening because of its specific proteolytic activity. In the past, it has been obtained from rennet in commercial manufacture. Milk-fed calves can be butchered and the fourth stomach removed freed of its food content. A complicated method is then used wherein the stomachs are dried, salted, and frozen. At factory points, the stomachs are washed, freed of salt and treated to remove surface fat. They are then stretched on racks and dried. The dried stomachs are often cold stored then ground and placed into large vats with a brine solution circulated through the skins until extraction of rennin is completed. The above procedure for preparing rennin is costly, and presents many difficulties in producing large amounts needed for commercial use in various applications throughout the world.